Hybrid component comprising a metal-reinforced ceramic matrix composite material

ABSTRACT

A hybrid metal-reinforced ceramic matrix composite (CMC) material component is provided having a body including a ceramic matrix composite material and a metal skeleton structure encompassing at least a portion of the body. A retaining structure carried by the metal skeleton structure is further included to induce a compressive force on the body to limit movement of the body and the metal skeleton structure relative to one another and enable the metal skeleton structure to carry a greater amount of an external load than the body.

STATEMENT REGARDING FEDERALLY SPONSORED DEVELOPMENT

Development for this invention was supported in part by Contract No.DE-FE0023955, awarded by the United States Department of Energy.Accordingly, the United States Government may have certain rights inthis invention.

FIELD

The present invention relates to high temperature components for use inhigh temperature environments such as gas turbines. More specifically,aspects of the present invention relate to hybrid components comprisinga metal-reinforced ceramic matrix composite (CMC) material and methodsfor manufacturing the same.

BACKGROUND

Gas turbines comprise a casing or cylinder for housing a compressorsection, a combustion section, and a turbine section. A supply of air iscompressed in the compressor section and directed into the combustionsection. The compressed air enters a combustion inlet and is mixed withfuel. The air/fuel mixture is then combusted to produce high temperatureand high pressure gas. This working gas is then ejected past a combustortransition and travels into the turbine section of the turbine.

The turbine section comprises rows of vanes which direct the working gasto the airfoil portions of the turbine blades. As working gas travelsthrough the turbine section, the gas causes the turbine blades torotate, thereby turning the rotor. The rotor is also attached to thecompressor section, thereby turning the compressor and also anelectrical generator for producing electricity. Hot gas is thenexhausted from the system. High efficiency may be achieved by heatingthe gas flowing through the combustion section to as high a temperatureas is practical. The hot gas, however, may degrade various turbinecomponents such as combustor components, transition ducts, vanes, ringsegments, exhaust components, and turbine blades that the hot gas passeswhen flowing through the turbine.

For this reason, strategies have been developed to protect suchcomponents from extreme temperatures, such as the development andselection of high temperature materials adapted to withstand theseextreme temperatures, and cooling strategies to keep the componentsadequately cooled during operation. For one, ceramic matrix composite(CMC) materials have been developed that comprise a ceramic matrixmaterial hosting a plurality of reinforcing fibers therein. While theseCMC materials provide excellent thermal protection properties, themechanical strength of CMC materials is still notably less than that ofcorresponding high temperature superalloy materials. Thus, thoughexcellent for resisting thermal protection in high temperatureapplications, CMC materials are not suitable for carrying structuralloads. One existing challenge in the art is thus how to apply CMCmaterials in regions of the gas turbine that are structurally loaded ina safe and cost-effective manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of thedrawings that show:

FIG. 1 is a perspective view of a component in accordance with an aspectof the present invention.

FIG. 2 is a perspective view of a component comprising a CMC body formedfrom stacked laminates in accordance with an aspect of the presentinvention.

FIG. 3 illustrates another embodiment of a metal skeleton structure inaccordance with an aspect of the present invention.

FIG. 4 illustrates a CMC body being inserted within a metal skeletonstructure in accordance with an aspect of the present invention.

FIG. 5 illustrates a CMC body comprising threaded ends structured tomate with fasteners in accordance with an aspect of the presentinvention.

FIG. 6 illustrates a CMC body having a thermal barrier coating about anexterior of the CMC body in accordance with an aspect of the presentinvention.

DETAILED DESCRIPTION

The present inventors have developed hybrid components, which satisfy aneed for high temperature components having increased thermal andcorrosion resistance while also having a desired strength in order tocarry structural loads. In one aspect, the component comprises a CMCmaterial reinforced with a metal skeleton structure. When employed in agas turbine, the CMC material of the component acts as a heat shieldbetween the hot inner gas flowing through the turbine while the metalskeleton structure both supports the CMC material and carries structuralloads to a greater extent than the CMC material. In certain embodiments,the metal skeleton structure may further comprise any attachment(s) orinterface(s) necessary for use of the device in a gas turbine. In thisway, the attachment(s) or interface(s) for the metal-reinforced CMCcomponents described herein may remain metal and nearly identical tocurrent configurations where the component is formed solely from asuperalloy, for example.

In accordance with one aspect, there is provided a hybrid componentincluding a body comprising a ceramic matrix composite material and ametal skeleton structure encompassing at least a portion of the body.The component further comprises a retaining structure carried by themetal skeleton structure effective to induce a compressive force on thebody to limit movement of the body and the metal skeleton structurerelative to one another and allow the metal skeleton structure to carrya greater amount of an external load than the body.

In accordance with another aspect, there is provided a method forforming a hybrid component. The method comprises mating a bodycomprising a ceramic matrix composite material with a metal skeletonstructure such that the metal skeleton structure encompasses at least aportion of the body. In addition, the method comprises supplying acompressive force on the body via a retaining structure carried by themetal skeleton structure which limits movement of the body and the metalskeleton structure relative to one another and allows the metal skeletonstructure to carry a greater amount of an external load than the body.

Now referring to the figures, there is shown an exemplary component 10in accordance with an aspect of the present invention comprising a body12 formed at least in part from a ceramic matrix composite (CMC)material 14. In certain embodiments, the body 12 may define a cavity 15therein. The body portion 12 (hereinafter “CMC body 12”) is at leastpartially encompassed about its exterior 16 by a metal skeletonstructure 18. In certain embodiments, a retaining structure 20 isprovided which limits or prevents movement of the CMC body 12 relativeto the metal skeleton structure 18, and vice-versa. In a particularembodiment, the retaining structure 20 is configured or structured suchthat it applies a compressive force to the CMC body 12 in order tomaintain the CMC body 12 in a fixed position while also allowing themetal skeleton structure 18 to bear further structural loads for thecomponent 10.

The CMC body 12 may be of any suitable size and dimension for itsintended application. In addition, the CMC body 12 is at least partiallyformed from the CMC material 14. The CMC material 14 may include aceramic matrix material that hosts a plurality of reinforcing fibers asis known in the art. In certain embodiments, the CMC material 14 may beanisotropic, at least in the sense that it can have different strengthcharacteristics in different directions. It is appreciated that variousfactors, including material selection and fiber orientation, can affectthe strength characteristics of a CMC material. The CMC material 14 maycomprise oxide, as well as non-oxide CMC materials. In an embodiment,the CMC material 14 may comprise alumina, and the fibers may comprise analuminosilicate composition consisting of approximately 70% alumina; 28%silica; and 2% boron (sold under the name NEXTEL™ 312). The fibers maybe provided in various forms, such as a woven fabric, blankets,unidirectional tapes, and mats. A variety of techniques are known in theart for making a CMC material, and such techniques can be used informing the CMC material 14 to be used herein for the body 12. ExemplaryCMC materials 14 for use herein are described in U.S. Pat. Nos.8,058,191; 7,745,022; 7,153,096; 7,093,359; and 6,733,907, the entiretyof each of which is hereby incorporated by reference. As mentioned, theselection of materials is not the only factor which governs theproperties of the CMC material 14 as the fiber direction may alsoinfluence the mechanical strength of the material, for example. As such,the fibers for the CMC material 14 may have any suitable orientationsuch as those described in U.S. Pat. No. 7,153,096.

In one embodiment, the CMC body 12 comprises a continuous solid bodyhaving as shown in FIG. 1. In another embodiment, as shown in FIG. 2,the body 12 may comprise a plurality of stacked laminate plates 22formed from the CMC material 14. In this embodiment, each of the stackedlaminate plates 22 may be cut to a desired shape via a laser cuttingprocess and stacked to provide the desired body 12. In certainembodiments, the stacked laminate plates 22 may be provided with asupport structure, such as a tie rod, extending through the stackedlaminates. The plates may further include suitable structures, such asretainers, for radial compression of the plates. Exemplary processes forforming a body of stacked laminates from a CMC material and associatedstructures are set forth in U.S. Pat. Nos. 8,528,339; 7,255,535;7,402,347; 7,247,002; 7,247,003; 7,198,458; and 7,153,096, for example,the entirety of each of which is hereby incorporated by reference. Someadvantages a stacked laminate structure include enabling CMC material toitself bear some structural loading via the individual plates, as wellas increasing a number of possible dimensions and configurations for anassociated component by controlling the structure of the component on alevel-by-level basis.

The metal skeleton structure 18 may comprise any metal material whichmay provide an added strength to the body 12 and may carry an extent ofloading on the component 10. In certain embodiments, the metal materialmay comprise an alloy material such as a Fe-based alloy, a Ni-basedalloy, a Co-based alloy as are well known in the art. In certainembodiments, the alloy may comprise a superalloy. The term “superalloy”may be understood to refer to a highly corrosion-resistant andoxidation-resistant alloy that exhibits excellent mechanical strengthand resistance to creep even at high temperatures. Exemplary superalloymaterials are commercially available and are sold under the trademarksand brand names Hastelloy, Inconel alloys (e.g., IN 738, IN 792, IN939), Rene alloys (e.g. Rene N5, Rene 41, Rene 80, Rene 108, Rene 142,Rene 220), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-750,ECY 768, 262, X45, PWA 1483 and CMSX (e.g. CMSX-4) single crystalalloys, GTD 111, GTD 222, MGA 1400, MGA 2400, PSM 116, CMSX-8, CMSX-10,PWA 1484, IN 713C, Mar-M-200, PWA 1480, IN 100, IN 700, Udimet 600,Udimet 500 and titanium aluminide, for example. In an embodiment, themetal skeleton structure 18 may be formed from a metal material having amelting temperature of from 450-600° C. due to the thermal protectionprovided by the CMC material 14.

The metal skeleton structure 18 may comprise any suitable dimensions,shape, or configuration that extends about at least a portion of theexterior 16 of the CMC body 12. Referring again to FIG. 1, in certainembodiments, the metal skeleton structure 18 may be configured to extendfrom a base portion 24 of the CMC body 12 to a top portion 26 of the CMCbody 12. In the exemplary embodiment shown in FIG. 1, the metal skeletonstructure 18 comprises a plurality of spaced apart ribs 28 thatencompass and provide structural support to the body 12. The ribs 28 maybe of any suitable number, size, and shape to provide a desired degreeof structural reinforcement to the body 12 and carry a structural loadthereon.

It is appreciated that the present invention, however, is not limited tothe embodiment of FIG. 1 and that the metal skeleton structure 18 mayalternatively comprise any other suitable structure which encompasses atleast a portion, if not all, of an exterior 16 of the CMC body 12 andwhich defines at least a plurality of openings 25 that allows at least aportion of the exterior 16 of the body 12 to remain exposed to thesurrounding environment. Without limitation, for example, the metalskeleton structure 18 may alternatively comprise another structure suchas a grid-like structure 30 as shown in FIG. 3 having a plurality ofintersecting metal members 32 defining openings 34.

The exposure of the exterior 16 of the CMC body 12 may offer significantadvantages, such as in an environment where the body 12 is exposed to acooling air flow, such as circulating shell air. In this way, the CMCbody 12 can be passively cooled and the amount of cooling air utilizedfor active cooling, which typically travels through or within the CMCbody 12, may be reduced. This not only allows for material and costsavings, but allows for higher inlet temperatures which in turn maytranslate to greater performance and efficiency. Moreover, in certainembodiments, cooling air reduction in a combustion system can be eitherused to: 1) reduce primary zone temperature (PZT) for a constant rotorinlet temperature (RIT) operation case, thereby leading to reductions inNOx emissions; or 2) increase RIT (for a constant NOx case), therebyleading to increase in power output and combined cycle (CC) efficiency.

In certain embodiments, the metal skeleton structure 18 and the CMC body12 comprise an interface which helps prevent rotation of the body 12relative to the metal skeleton structure 18, or vice-versa. For example,in the embodiment shown in FIG. 4, the body 12 may comprise a pluralityof channels 36, each channel 36 having a depth such that at least aportion of a respective rib 28 of a metal skeleton 18 may be receivedand disposed therein. In a particular embodiment, the ribs 28 of themetal skeleton 18 may be slidably inserted within the channels 36 toprovide the desired interface between the CMC body 12 and the metalskeleton 18 for the component 10. These channels 36 may also be providedin the stacked laminate structure of FIG. 2. In an alternativeembodiment, the ribs 28 of the metal support structure 18 may insteadcomprise channels 36 therein which are configured to receivecorresponding portions of the CMC body 12 therein.

The retaining structure 20 may be any suitable structure for at leastmaintaining contact between the CMC body 12 and the metal skeleton 18.In certain embodiments, the retaining structure 20 is further configuredto induce a compressive force on the CMC body 12. In this way, the metalskeleton structure 18 may be configured to receive an external loadthereon instead of the structurally weaker CMC body 12. Referring againto FIG. 1, by way of example only, the retaining structure 20 maycomprise a retaining ring 38 which is configured to engage and fit overan exterior portion 39 the ribs 28 of the metal skeleton 18. Theretaining ring 20 may further include channels or clasps 40 as shownwithin which the ribs 28 may be engaged within or otherwise inserted.Although the retaining ring 38 is shown as fitting over a topmostportion of the metal skeleton structure 18, it is understood that thepresent invention is not so limited. Further, the retaining ring 38 maycomprise one or more additional retaining rings, or alternatively maycomprise any other suitable structure.

The component 10 and/or retaining structure 20 may include any furtherstructure(s) effective to at least assist in providing a compressiveforce on the CMC material 12. In an embodiment, for example, as shown inFIG. 5, a plurality of fasteners 42 may be provided which are configuredto mate with threaded ends 44 on the ribs 28. The retaining ring 38 isomitted from FIG. 5, but referring again to FIG. 1, it can beappreciated that as fasteners 42 (such as nuts or bolts) are tightened,the fasteners 42 may increasingly cause the retaining ring 38 and/ormetal skeleton structure 18 to place a greater compressive load or forceon the CMC body 12. This load or force not only maintains the CMC body12 in a fixed position relative to the metal skeleton structure 18, butalso forces the metal skeleton structure 18 to carry at least an amountof an external load upon a further application of an external load tothe component 10. In this way, the CMC body 12 may primarily carrythermal loads while the metal skeleton structure 18 may primarily carrystructural loads upon use of the component in an environment exposingthe component 10 to such loads, such as in a gas turbine environment.

In accordance with another aspect of the present invention, the metalskeleton structure 18 may be fabricated so as to be formed with orotherwise may include any mating parts necessary for the component 10 tomate with another component. When not integral components, the matingparts may be joined to the metal support structure 18 via any suitablemethod such as welding or soldering. Referring again to FIG. 1, forexample, the component 10 may include a flange 44 on a base portion 24thereof for attaching the component 10 to another component which isconfigured to mate with or receive the flange 44. Further, the component10 may comprise a plurality of tabs 45 on a top portion 26 thereof forattachment of the component 10 to a combustor, for example. In anembodiment, the flange 44, tabs 45, or any other suitable matingstructures are formed from metal. In this way, the mating parts for thecomponent 10 may remain metal and nearly identical to currentconfigurations. As such, the components described herein can be easilyincorporated into existing turbine systems.

In accordance with another aspect, to afford greater thermal protectionto the component 10, a thermal barrier coating (TBC) 48 may be appliedto an internal surface 50 of the CMC body 12 to prevent oxidation of orthermal damage to the CMC material since the internal surface 50 isexposed to high temperatures as shown in FIG. 6. FIG. 6 is across-section taken at line A-A of FIG. 4. In one embodiment, thethermal barrier coating 48 may comprise a friable graded insulation(FGI) as is known in the art. See, for example, U.S. Pat. Nos.7,563,504; 7,198,462; 6,641,907; 6,676,783; and 6,235,370, each of whichare incorporated by reference herein. In further embodiments, suchthermal barrier coatings may instead or also be applied to an outerperiphery of the CMC body 12.

In accordance with another aspect of the present invention, there areprovided methods for manufacturing a metal-reinforced CMC component. Inone embodiment, as was shown in FIG. 4, a metal skeleton structure 18 asdescribed herein may be first fabricated according to desiredspecifications, or otherwise provided from a commercial or suitablesource. The metal skeleton structure 18 may be cast or otherwise formedas a single piece, or may alternatively require joining of one of moreof its components to remaining portions of the metal skeleton structure18. Thereafter, the CMC body 12 as described herein may be providedwhich may be configured for slidable insertion into the metal skeletonstructure 18 via aligning the ribs 28 with channels 36 in the CMC body12 and sliding the CMC body 12 therein in the direction of arrow B asshown.

Thereafter, referring again to FIG. 1, the retaining structure 20 may beplaced on an exterior of the metal skeleton structure 18 and theretaining structure 20 secured or otherwise tightened to preventmovement of the CMC body 12 relative to the metal skeleton structure 18.For example, clasps 40 carried by the retaining structure 20 may engageribs 28 therein. Thereafter, as described previously, fasteners 42 maybe tightened on threaded ends 44 of the ribs 28 such that the retainingstructure 20 and/or metal skeleton structure 18 exerts a compressiveload on the CMC body 12. This compressive load not only keeps the CMCbody 12 in place, but also allows the metal skeleton structure 18 tobear further external loads.

While various embodiments of the present invention have been shown anddescribed herein, it will be obvious that such embodiments are providedby way of example only. Numerous variations, changes and substitutionsmay be made without departing from the invention herein. Accordingly, itis intended that the invention be limited only by the spirit and scopeof the appended claims.

1. A hybrid component comprising: a body comprising a ceramic matrixcomposite material; a metal skeleton structure encompassing at least aportion of the body and extending between a base and a top of the body;and a retaining structure carried by the metal skeleton structureeffective to induce a compressive force on the body to limit movement ofthe body and the metal skeleton structure relative to one another andallow the metal skeleton structure to carry a greater amount of anexternal load than the body.
 2. The component of claim 1, wherein themetal skeleton structure comprises an alloy material.
 3. The componentof claim 2, wherein the alloy material has a melting point of from450-600° C.
 4. The component of claim 1, wherein the metal skeletonstructure comprises a mating structure such that the component can beconnected to another structure.
 5. The component of claim 4, wherein themating structure comprises a circumferential flange or tabs forattachment of the component to another structure.
 6. The component ofclaim 1, wherein the metal skeleton structure comprises a plurality ofribs extending radially from a base portion thereof.
 7. The component ofclaim 6, wherein one of the body and the ribs comprises a plurality ofchannels configured to receive a portion of the other of the body andthe ribs therein.
 8. The component of claim 7, wherein the bodycomprises a plurality of channels, and wherein the ribs are configuredfor slidable insertion into the plurality of channels.
 9. The componentof claim 1, wherein the retaining structure comprises a retaining ringdisposed about the metal skeleton structure and a plurality of fastenersconfigured to cause the retaining ring to induce a compressive force onthe body upon tightening of the fasteners.
 10. The component of claim 1,wherein the body comprises a plurality of stacked laminate plates, eachplate comprising the ceramic matrix composite material.
 11. A method forforming a hybrid component comprising: mating a body comprising aceramic matrix composite material with a metal skeleton structure suchthat the metal skeleton structure encompasses at least a portion of thebody and extends between a base and a top of the body; and supplying acompressive force on the body via a retaining structure carried by themetal skeleton structure which limits movement of the body and the metalskeleton structure relative to one another and allows the metal skeletonstructure to carry a greater amount of an external load than the body.12. The method of claim 11, wherein the supplying is done by: disposinga retaining ring about the metal skeleton structure; and tightening aplurality of fasteners on the retaining ring to induce a compressiveforce on the body.
 13. The method of claim 11, wherein the metalskeleton structure comprises a plurality of ribs, and wherein on of thebody and the ribs comprises a plurality of channels configured toreceive a portion of the other of the body and the ribs therein.
 14. Themethod of claim 13, wherein the body comprises a plurality of channels,and wherein the method further comprises slidably inserting the ribsinto the channels of the body.
 15. The method of claim 11, wherein themetal skeleton structure comprises an alloy material.
 16. The method ofclaim 11, wherein the alloy material has a melting point of from450-600° C.
 17. The method of claim 11, wherein the metal skeletonstructure comprises a mating structure such that the component can beconnected to another structure.
 18. The method of claim 11, wherein themating structure comprises a circumferential flange for attachment ofthe component to another structure.
 19. The method of claim 11, whereinthe body comprises a plurality of stacked laminate plates, each platecomprising the ceramic matrix composite material.